(Digital Presentation) Electrochemical Finishing of Mo Feedhorn Arrays

Abstract

Powder bed methods of additive manufacturing (AM) use an electron beam (EBM) to sequentially melt powder, layer by layer, to build up a 3-dimensional object directly from a powder bed according to a computer aided design file. With EBM. there are four steps to build each layer in a build. First, the beam is scanned to preheat the powder bed without melting, second, the contours (outer edge) of the area to be melted is traced and powder melted, third, the hatch (area within the contours) is melted and finally any supports that need to be built to support higher layers of the part being built are added.The major concerns for incorporation of AM into structural parts are (1) microstructural anisotropy/inhomogeneity, (2) porosity and (3) surface finish that is strongly dependent on the orientation of the surface relative to the build direction. Improving the surface finish is critical for certain applications. While finish machining can be used where surfaces are accessible, one benefit of the complexity of part shape is the possibility of building parts with internal passages, inaccessible to machining.Therefore, this paper will discuss recent developments toward the demonstration of a process to electrochemically finish the feedhorn arrays produced with Mo by EBM additive manufacturing. Specifically, we will discuss developments toward achieving optimal electrochemical processing conditions, surface finish, nominal tooling, and performance. Unlike conventional surface finishing processes that either use media or machine tools to physically modify the surface, electrochemistry can be used as a non-contact flexible approach, to finish hard to reach surfaces such as the internal channels of refractory materials that maybe inaccessible to conventional processes. This paper will focus on pulse/pulse reverse electrofinishing processes developed by Faraday Technology and the technique to scale this approach to functional parts of interest. Acknowledgements: The financial support of DOE Contract No. DE-SC0020783 is acknowledged.